One conventional method of forming multiribbed belts is to form a belt sleeve having an inner compression rubber section. Upon completion of the vulcanization of the sleeve, grooves are cut into the compression section to define the longitudinally extending parallel ribs of the multiribbed belt.
It is common to provide, in the compression rubber, transversely extending staple fibers for providing improved transverse strength and rigidity, while yet permitting facilitated flexing of the belt about the pulleys, etc., of the drive system. When such grooves are cut into the compression section, a substantial amount of rubber and fibers are removed As a result, the forming of such multiribbed belts in this manner is relatively expensive.
Another method of forming such multiribbed belts is to form the compression section on a cylindrical mandrel having radially outwardly projecting ribs about which the unvulcanized compression rubber is urged during the vulcanization process so as to define grooves in the compression rubber section, with the ribs lying on opposite sides of the grooves.
While this latter method of formation of multiribbed belts eliminates the rubber and staple fiber loss in the first above-described method of manufacture, a serious problem arises in the latter manufacture in that the staple fibers are urged away from their transversely extending orientation to a relatively high angle thereto In such an orientation, the fibers offer substantially reduced transverse strength characteristics to the belt and cause a stiffening of the belt outwardly relative to the compression section, resulting in an inferior belt construction.